Method of manufacturing a wrap around shield for a perpendicular write pole using a laminated mask with an endpoint detection layer

ABSTRACT

A method for manufacturing a magnetic write pole and trailing wrap around magnetic shield for use in a perpendicular magnetic data recording system. The method includes the use of a hard mask structure with end point detection material embedded in a hard mask material. The novel hard mask structure provides the mill resistance of a hard mask, with the end point detection advantages of an end point detection layer.

FIELD OF THE INVENTION

The present invention relates to perpendicular magnetic recording and more particularly to a novel trailing wrap around magnetic shield design and a method for manufacturing such a shield design.

BACKGROUND OF THE INVENTION

The heart of a computer's long term memory is an assembly that is referred to as a magnetic disk drive. The magnetic disk drive includes a rotating magnetic disk, write and read heads that are suspended by a suspension arm adjacent to a surface of the rotating magnetic disk and an actuator that swings the suspension arm to place the read and write heads over selected circular tracks on the rotating disk. The read and write heads are directly located on a slider that has an air bearing surface (ABS). The suspension arm biases the slider toward the surface of the disk, and when the disk rotates, air adjacent to the disk moves along with the surface of the disk. The slider flies over the surface of the disk on a cushion of this moving air. When the slider rides on the air bearing, the write and read heads are employed for writing magnetic transitions to and reading magnetic transitions from the rotating disk. The read and write heads are connected to processing circuitry that operates according to a computer program to implement the writing and reading functions.

The write head traditionally includes a coil layer embedded in first, second and third insulation layers (insulation stack), the insulation stack being sandwiched between first and second pole piece layers A gap is formed between the first and second pole piece layers by a gap layer at an air bearing surface (ABS) of the write head and the pole piece layers are connected at a back gap. Current conducted to the coil layer induces a magnetic flux in the pole pieces which causes a magnetic field to fringe out at a write gap at the ABS for the purpose of writing the aforementioned magnetic transitions in tracks on the moving media, such as in circular tracks on the aforementioned rotating disk.

In recent read head designs a spin valve sensor, also referred to as a giant magnetoresistive (GMR) sensor, has been employed for sensing magnetic fields from the rotating magnetic disk. The sensor includes a nonmagnetic conductive layer, hereinafter referred to as a spacer layer, sandwiched between first and second ferromagnetic layers, hereinafter referred to as a pinned layer and a free layer. First and second leads are connected to the spin valve sensor for conducting a sense current, therethrough. The magnetization of the pinned layer is pinned perpendicular to the air bearing surface (ABS) and the magnetic moment of the free layer is located parallel to the ABS, but free to rotate in response to external magnetic fields. The magnetization of the pinned layer is typically pinned by exchange coupling with an antiferromagnetic layer.

The thickness of the spacer layer is chosen to be less than the mean free path of conduction electrons through the sensor. With this arrangement, a portion of the conduction electrons is scattered by the interfaces of the spacer layer with each of the pinned and free layers. When the magnetizations of the pinned and free layers are parallel with respect to one another, scattering is minimal and when the magnetizations of the pinned and free layer are antiparallel, scattering is maximized. Changes in scattering alter the resistance of the spin valve sensor in proportion to cos Θ, where Θ is the angle between the magnetizations of the pinned and free layers. In a read mode the resistance of the spin valve sensor changes proportionally to the magnitudes of the magnetic fields from the rotating disk. When a sense current is conducted through the spin valve sensor, resistance changes cause potential changes that are detected and processed as playback signals.

When a spin valve sensor employs a single pinned layer it is referred to as a simple spin valve. When a spin valve employs an antiparallel (AP) pinned layer it is referred to as an AP pinned spin valve. An AP spin valve includes first and second magnetic layers separated by a thin non-magnetic coupling layer such as Ru. The thickness of the spacer layer is chosen so as to be antiparallel coupled to the magnetizations of the ferromagnetic layers of the pinned layer. A spin valve is also known as a top or bottom spin valve depending upon whether the pinning layer is at the top (formed alter the free layer) or at the bottom (before the free layer).

The spin valve sensor is located between first and second nonmagnetic electrically insulating read gap layers and the first and second read gap layers are located between ferromagnetic first and second shield layers. In a merged magnetic head a single ferromagnetic layer functions as the second shield layer of the read head and as the first pole piece layer of the write head. In a piggyback head the second shield layer and the first pole piece layer are separate layers.

Magnetization of the pinned layer is usually fixed by exchange coupling one of the ferromagnetic layers (API) with a layer of antiferromagnetic material such as PtMn. While an antiferromagnetic (AFM) material such as PtMn does not in and of itself have a magnetization, when exchange coupled with a magnetic material, it can strongly pin the magnetization of the ferromagnetic layer.

In order to meet the ever increasing demand for improved data rate and data capacity, researchers have recently been focusing their efforts on the development of perpendicular recording systems. A traditional longitudinal recording system, such as one that incorporates the write head described above, stores data as magnetic bits oriented longitudinally along a track in the plane of the surface of the magnetic disk. This longitudinal data bit is recorded by a fringing field that forms between the pair of magnetic poles separated by a write gap.

A perpendicular recording system, by contrast, records data as magnetizations oriented perpendicular to the plane of the magnetic disk. The magnetic disk has a magnetically soft underlayer covered by a thin magnetically hard top layer. The perpendicular write head has a write pole with a very small cross section and a return pole having a much larger cross section. A strong, highly concentrated magnetic field emits from the write pole in a direction perpendicular to the magnetic disk surface, magnetizing the magnetically hard top layer. The resulting magnetic flux then travels through the soft underlayer, returning to the return pole where it is sufficiently spread out and weak that it will not erase the signal recorded by the write pole when it passes back through the magnetically hard top layer on its way back to the return pole.

One of the features of perpendicular recording systems is that the high coercivity top layer of the magnetic medium has a high switching field. This means that a strong magnetic field is needed to switch the magnetic moment of the medium when writing a magnetic bit of data. In order to decrease the switching field and increase recording speed, attempts have been made to angle or “cant” the write field being emitted from the write pole. Canting the write field at an angle relative to the normal of the medium makes the magnetic moment of the medium easier to switch by reducing the switching field. Modeling has shown that a single pole writer in a perpendicular recording system can exhibit improved transition sharpness (i.e. better field gradient and resolution), achieve better media signal to noise ratio, and permit higher coercive field media for higher areal density magnetic recording if, according to the Stoner-Wohlfaith model for a single particle, the effective flux field is angled. A method that has been investigated to cant the magnetic field has been to provide a trailing magnetic shield adjacent to the write head, to magnetically attract the field from the write pole.

The trailing shield can be a floating design, in that the magnetic trailing shield is not directly, magnetically connected with the other structures of the write head. Magnetic field from the write pole results in a flux in the shield that essentially travels through the magnetic medium back to the return pole of the write head. Alternatively, the trailing shield can be magnetically connected with other magnetic portion of the write head such as the write pole and return pole.

Various dimensions of the shield are critical for the trailing shield to operate correctly. For instance, effective angling or canting of the effective flux field is optimized when the write pole to trailing shield separation (gap) is about equal to the head to soft underlayer spacing (HUS) and the trailing shield throat height is roughly equal to half the track-width of the write pole. This design improves write field gradient at the expense of effective flux field. To minimize effective flux field lost to the trailing shield and still achieve the desired effect, the gap and shield thickness are adjusted to minimize saturation at the shield and effective flux field lost to the shield respectively. In order for a trailing shield to function optimally, the thickness of the trailing shield gap must be tightly controlled. Therefore, there is a need for a means for accurately controlling such trailing gap thickness during manufacture.

In addition, the track width and shape of the write pole must he tightly controlled. The write pole is preferably configured with a trapezoidal shape and preferably has a straight fiat trailing edge. The write pole can be formed by ion milling a magnetic material at such an angle or combination of angles that a write pole having the desired trapezoidal shape is formed. A challenge to creating such a well defined pole structure is that the mask used during ion milling must be thick and robust to withstand the aggressive ion mill and form a write pole having a well controlled track width and flat, straight trailing edge. Such a mask structure does not lend itself well to functioning as a trailing shield gap, because, alter the ion milling, the remaining mask is not flat and does not have the desired small, well controlled thickness to function as a trailing shield gap.

Therefore, there is a need for a method for manufacturing a perpendicular write head that can produce a write pole having a well controlled track width and flat trailing edge, while still producing a trailing, wrap around shield that has a trailing gap with a well controlled thickness and shape.

SUMMARY OF THE INVENTION

The present invention provides a method for manufacturing a magnetic write head for perpendicular recording having a wrap around trailing shield. The method includes depositing a magnetic write pole material over a substrate and then forming mask structure over the magnetic write pole material. The mask structure includes a hard mask-layer with an end point detection layer embedded therein at a desired elevation within the hard mask layer. The end point detection layer can be a material that is essentially the same as the rest of the hard mask except with a small amount of an easily detectable element added therein.

An ion milling operation is performed to remove magnetic write pole material not covered by the mask structure, to form the write pole. A non-magnetic material is then deposited and a reactive ion mill is performed to remove the non-magnetic material until the end point detection layer has been reached and removed.

The present invention provides end point detection while reducing the number of mask layers that, must be deposited, while maximizing the amount of ion mill resistant, material in the hard mask structure. The invention uses innovative hard mask materials, which have the end point detection marker embedded in the hard mask material in low-concentration. In this way, the hard mask material retains its low ion mill rate properties while also serving as an end point detection marker.

These and other features and advantages of the invention will be apparent upon reading of the following detailed description of preferred embodiments taken in conjunction with the FIGS. in which like reference numerals indicate like elements throughout

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the nature and advantages of this invention, as well as the preferred mode of use, reference should be made to the following detailed description read in conjunction with the accompanying drawings which are not to scale.

FIG. 1 is a schematic illustration of a disk drive system in which the invention might be embodied;

FIG. 2 is an ABS view of a slider, taken from line 2-2 of FIG. 1, illustrating the location of a magnetic head thereon;

FIG. 3 is a cross sectional view, taken from line 3-3 of FIG. 2 and rotated 90 degrees counterclockwise, of a magnetic head according to an embodiment of the present invention;

FIG. 4 is an ABS view of the write head taken from line 4-4 of FIG. 3

FIG. 5 is an enlarged view of a write pole and surrounding structure;

FIGS. 6-15 are ABS views similar to that of FIGS. 4 and 5, showing a magnetic head in various intermediate stages of manufacture and illustrating a method of manufacturing a magnetic head according to an embodiment of the invention; and

FIGS. 16-18 are views of a magnetic write head in various intermediate stages of manufacture illustrating a method of manufacturing a write head according to an alternate embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description is of the best embodiments presently contemplated for carrying out this invention. This description is made for the purpose of illustrating the general principles of this invention and is not meant to limit the inventive concepts claimed herein.

Referring now to FIG. 1, there is shown a disk drive 100 embodying this invention. As shown in FIG. 1, at least one rotatable magnetic disk 112 is supported on a spindle 114 and rotated by a disk drive motor 118. The magnetic recording on each disk is in the form of annular patterns of concentric data tracks (not shown) on the magnetic disk 112.

At least one slider 113 is positioned near the magnetic disk 112, each slider 113 supporting one or more magnetic head assemblies 221. As the magnetic disk rotates, slider 113 moves radially in and out over the disk surface 122 so that the magnetic head assembly 121 may access different tracks of the magnetic disk where desired data, are written Each slider 113 is attached to an actuator arm 119 by way of a suspension 115. The suspension 115 provides a slight spring force which biases slider 113 against the disk, surface 122. Each actuator arm 119 is attached to an actuator means 127. The actuator means 127 as shown in FIG. 1 may be a voice coil motor (VCM). The VCM comprises a coil movable within a fixed magnetic field, the direction and speed of the coil movements being controlled by the motor current signals supplied by controller 129.

During operation of the disk storage system, the rotation of the magnetic disk 112 generates an air bearing between the slider 113 and the disk surface 122 which exerts an upward force or lift on the slider. The air bearing thus counter-balances the slight spring force of suspension 115 and supports slider 113 off and slightly above the disk surface by a small, substantially constant spacing during normal operation.

The various components of the disk storage system are controlled in operation by control signals generated by control unit 129, such as access control signals and internal clock signals. Typically, the control unit 129 comprises logic control circuits, storage means and a microprocessor. The control unit 129 generates control signals to control various system operations such as drive motor control signals on line 123 and head position and seek control signals on line 128. The control signals on line 128 provide the desired current profiles to optimally move and position slider 113 to the desired data track on disk 112. Write and read signals are communicated to and from write and read heads 121 by way of recording channel 125.

With reference to FIG. 2, the orientation of the magnetic head 121 in a slider 113 can be seen in more detail. FIG. 2 is an ABS view of the slider 113, and as can be seen the magnetic head including an inductive write head and a read sensor, is located at a trailing edge of the slider. The above description of a typical magnetic disk storage system, and the accompanying illustration of FIG. 1 are for representation purposes only. It should be apparent that disk storage systems may contain a large number of disks and actuators, and each actuator may support a number of sliders.

With reference now to FIG. 3, the magnetic head 221 for use in a perpendicular magnetic recording system is described. The head 221 includes a write element 302 and a read element 304 that includes a magnetoresistive sensor 305. The read sensor 305 is preferably a giant magnetoresistive (GMR) sensor and is preferably a current perpendicular to plane (CPP) GMR sensor. CPP GMR sensors are particularly well suited for use in perpendicular recording systems. However, the sensor 305 could be another type of sensor such as a current in plane (CIP) GMR sensor or, a tunnel junction sensor (TMR) or some other type of sensor The sensor 305 is located between and insulated from first and second magnetic shields 306, 308 and embedded in a dielectric material 307. The magnetic shields, which can be constructed of for example CoFe or NiFe, absorb magnetic fields, such as those from up-track or down track data signals, ensuring that the read sensor 304 only detects the desired data track located between the shields 306, 308. A non-magnetic, electrically insulating gap layer 309 may be provided between the shield 308 and the write head 302.

With continued reference to FIG. 3, the write element 302 includes a write pole 310 that is magnetically connected with a magnetic shaping layer 312, and is embedded within an insulation material 311. The write pole 310 has a small cross section at the air bearing surface and is constructed of a material having a high saturation moment, such as NiFe or CoFe. The shaping layer 312 is constructed of a magnetic material such as CoFe or NiFe

The write element 302 also has a return pole 314 that preferably has a surface exposed at the ABS and has a cross section parallel with the ABS surface that is much larger than that of the write pole 310. This can be seen more clearly with reference to FIG. 4, which shows the head 221 as viewed from the air bearing surface (ABS). The return pole 314 is magnetically connected with the shaping layer 312 by a back gap portion 316. The return pole 314 and back gap 316 can be constructed of, for example, NiFe, CoFe or some other magnetic material.

An electrically conductive write coil 317, shown in cross section in FIG. 3, passes through the write element 302 between the shaping layer 312, and the return pole 314. The write coil 317 is surrounded by an electrically insulating material 320 that electrically insulates the turns of the coil 317 from one another and electrically isolates the coil 317 from the surrounding magnetic structures 310, 312, 316, 314. When a current passes through the coil 317, the resulting magnetic field causes a magnetic flux to flow through the return pole 314, back gap 316, shaping layer 312 and write pole 310. This magnetic flux causes a write field to be emitted toward an adjacent magnetic medium (not shown in FIGS. 3 and 4). The shaping layer 312 is also surrounded by an insulation layer 321 which separates the shaping layer 312 from the ABS. The insulation layers 320, 321, 311 can all be constructed of the same material, such as alumina (Al₂O₃) or of different electrically insulating materials.

The write head element 302 also includes a trailing shield 322. With reference to FIG. 4, the trailing shield 322 wraps around the write pole 310 to provide side shielding as well as trailing shielding from stray magnetic fields. These stray magnetic fields can be from portions of the write head 302 itself, or could also be from adjacent track signals or from magnetic fields from external sources.

With reference now to FIG. 5 the configuration of the write pole 310 and the surrounding portions of the trailing shield 322 are shown enlarged and in greater detail. The write pole 310 has a trailing edge 402 and a leading edge 404. The terras trailing and leading are with respect to the direction of travel along a data track when the write head 302 is in use. The write pole 310 also preferably has first and second laterally opposing sides 406, 408 that are configured to define a width at the leading edge 404 that is narrower than the width at the trailing edge 402, forming a write pole 310 having a trapezoidal shape. This trapezoidal shape is useful in preventing adjacent track writing due to skew of the write head 302 when the head 302 is located at extreme outer or inner positions over the disk, however, this trapezoidal shape of the write head 310 is not necessary to practice the present invention.

With continued reference to FIG. 5, the magnetic trailing shield 322 is separated from each side 406, 408 of the write pole 310 by a side gap 410. The trailing shield 322 is also separated from the trailing edge 402 of the write pole 310 by a trailing gap 412. The thickness of each of the side gaps 410 is preferably about 2 to 4 or about 3 times the thickness of the trailing gap 412. The materials defining and filling the side and trailing gaps 410, 412 are non-magnetic materials. The trailing gap 412 is filled with a non-magnetic material 416, which may be alumina or may be some other non-magnetic material. Similarly, the side gaps 410 include a non-magnetic side gap material 414 which may be, for example, conformally deposited alumina.

As can be seen with reference to FIG. 5, the trailing shield 322 may or may not be configured with notches 418 at either side of the write pole 310. The notches can be described as extensions of the side gaps 410 that extend in the trailing direction slightly beyond the trailing edge gap 412. These optional notches 418 can be constructed by a manufacturing process that will be described below, and can improve the magnetic performance of the write element 302. Preferably the notches have a notch depth (ND) that is less than or equal to 30 nm. The trailing shield 322 can be constructed, of a magnetic material such as NiFe.

With reference now to FIGS. 6 through 15, a method for constructing a write pole and a wrap around trailing shield according to an embodiment is described. The method described with reference to FIGS. 6-15 can form a trailing shield with notches 418 and with a very well controlled trailing gap thickness 412 as described above with reference to FIG. 5.

With particular reference to FIG. 6, a substrate layer 600 is provided. The substrate 600 can include the non-magnetic till layer 321 and the shaping layer 312 on which the write pole 310 is to be formed (FIG. 3). One or more layers of write pole material 602 are deposited over the substrate 600. The write pole layer 604 preferably is a lamination of magnetic layers such as CoFe with thin layers of non-magnetic material sandwiched between the magnetic layers.

A plurality of mask layers 604 are deposited over the write pole layer (lamination) 602. The mask layers include a first hard mask structure 603. The first hard mask layer 603 includes a first sub-layer 606 constructed of a material that has a high resistance ion milling, preferably alumina (Al₂O₃). The first sub-layer is constructed to a thickness to define a trailing gap thickness in the finished trailing shield. For example, the first sub-layer 606 can be constructed to a thickness of 15-25 nm or about 20 nm. The first hard mask layer further includes a second sub-layer 608. The second sub-layer is preferably constructed of a material that is resistant to ion milling, but is removal by a process such as reactive ion etching (RIE) The second sub-layer 608 can, therefore, be constructed of, for example, Si₃N₄. The second sub-layer 608 (which can also be referred to as a RIEable layer) has a thickness that is chosen to define the size of a trailing shield notch such as the notch 418 described with reference to FIG. 5 Therefore, the second sub-layer 608 can have a thickness of 25-35 nm or about 30 nm. In addition, the first hard mask layer 603 includes a third sub-layer 610. The third sub-layer is constructed of a material that functions both as a hard mask material and also as an end point detection layer. Therefore, the third sub-layer 610 should be constructed of a material that can be easily detected, such as by Secondary Son Mass Spectroscopy (SIMS) and which also is very resistant ion milling. The third sub-layer can, therefore, be constructed of hard mask material such as alumina with a small amount of a detectable material such as Ti, (ie. AlTiO). The third sub-layer 610 can have, for example 2-10 atomic percent or about 5 atomic percent Ti. The use of alumina in the hard mask sub-layers 606, 610 is by way of example only, however. Other hard ion mill resistant materials such as Diamond Like Carbon (DLC), BeO, etc. could be used as well. In addition, the use of Ti as a detectable material in the third sub-layer is by way of example only. The detectable material element can be any element on the periodic table that does not have isotopic overlap with the milling gas (used in a reactive ion milling operation to be described below), atmospheric gases nor the layers below the hard mask layer. Other detectable materials that could be used include Ta, V, Cr, Cu, Zr, Nb, Mo, Ru, Rh, Hr, W, Re, Os, Ir, Pt and Au. The third sub-layer advantageously maintains the hard mask properties of it majority material (for example alumina) while also being detectable by the incorporation of a small amount of detectable material.

With continued reference to FIG. 6, the mask layers 604 further include a first image transfer layer 612, which can be a soluble polyimide layer such as DURIMIDE®. The first image transfer layer can be, for example, 1000 to 1400 nm or about 1200 nm. Another hard mask layer 614 such as, for example silicon dioxide (SiO₂) can be deposited over the first image transfer layer, and an antireflective layer 616, which can also be a soluble polyimide such as DURIMIDE® can be formed over the second hard mask 614. The top hard mask 614 can be 60 to 1.50 nm thick or about 90 nm thick. The second, or top, image transfer layer 616 can be 100 to 130 nm thick or about 115 nm thick. A layer of resist material such as photoresist or e-beam resist 618 is deposited at the top of the mask layers 604.

With reference now to FIG. 7, the resist layer is photolithographic-ally patterned, such as by photolithography or electron beam (e-beam) lithography. After exposure, the photo layer is developed in an appropriate developing solution. The photo layer 618 is patterned to have a width to define a desired write pole track width, as will be further described herein below.

With reference now to FIG. 8, a reactive ion etch (RIE) 802 is performed to transfer the image of the photoresist mask 618 onto the underlying image transfer layers 612, 618 and top hard mask 616, by removing portions of the layers that are not covered by the photo mask 802. The RIE 802 can be performed in several steps using both oxygen chemistry such as O₂ and CO₂ and fluorine chemistry such as a CF₄ or CHF₃. Then, with reference to FIG. 9, a reactive ion mill 902 is performed to transfer the image of the overlying mask layers 612, 614, 616 and 618 onto the underlying first hard mask structure 603. The reactive ion milling 902 can be performed with an Ar or CHF₃ based process depending on the materials used in the hard mask layers 606, 610 and end point detection layer 608. The above described material removal processes are by way of example, however. The choice of which material removal processes are used to transfer the image of the photo layer 618 onto the underlying mask layers 606-616 will depend upon the materials used for these layers 606-616.

With reference now to FIG. 10, an ion milling operation 1002 is performed to remove portions of the write pole material 602 that are not protected by the mask layers 604. The ion milling is preferably performed at an angle (or various angles) with respect to normal in order to configure the write pole 602 with the desired trapezoidal shape as shown. This is, however, not necessary to the practice of the present invention. It can be seen that the ion milling 1002 removes the photo layer 618 top image transfer layer 616 top hard mask 614 and at least a portion of the image transfer 612 in the process of forming the write pole 602. Then, with reference to FIG. 11, the remaining image transfer layer 612 is removed such as by a tetraethylammonium hydroxide (TMAH) based etching followed by an N-methylpyrrolidinone (NMP) photoresist strip. This leaves the first hard mask structure 603.

With reference now to FIG. 12, a layer of non-magnetic, side gap material 1202 is deposited. The side gap material 1202 is preferably alumina, although other non-magnetic materials could be used as well. This layer 1202 is preferably deposited by a conformal deposition method such as atomic layer deposition, chemical vapor deposition, etc. Although various material and deposition method could be used for the layer 1202, the layer will be referred to herein as ALD layer 1202.

Then, with reference to FIG. 13, a material removal process 1302 is performed to remove a portion of the ALD layer 1202. The material removal process is preferably an ion mill, performed in an Ar chemistry with end point detection (EPD). The third sub-layer 610 (FIG. 12) can be used to indicate when the ion milling 1302 should be terminated. As mentioned above, the third sub-layer 610 includes an element, such as Ti, that can be easily detected, such as by SIMS. Therefore, when it has been determined that the third sub-layer 610 has been removed, the ion milling 1302 can be terminated. The ton milling 1302 is preferably performed at an angle that is chosen remove material at a high etch rate to form an upper surface on the layers 1202, 608 that is as flat as possible. It has been found that an optimal ion mill angle for this purpose is about 45 to 65 degrees or about 55 degrees with respect to normal. When the end point detection layer 608 has been reached, its presence can be easily detected in the ion mill tool, indicating that ion milling 1302 can be terminated.

Then, with reference to FIG. 14, a reactive ion etch (RIE) 1402 is performed to remove the third sub-layer 608 leaving the first sub-layer 606 exposed, and having a straight fiat surface. The RIE 1402, which may be performed in a fluorine based chemistry, preferentially removes the end point detection layer 608, so that very little if any of the first hard mask layer 606 is removed. This results, not only in the layer 606 having a straight, fiat, surface, but also in the layer 606 having a very well controlled thickness, which thickness can be controlled at deposition of the layer 606. With reference now to FIG. 15, a wrap around trailing shield 1502 can be formed by first depositing an electrically conductive, magnetic seed layer and then electroplating to deposit a magnetic material. The seed layer and magnetic material can both be, for example, NiFe. It can be seen that the thickness of the first sub-layer 606 defines the trailing gap thickness. However, the deposition of the magnetic material 1502 can include first depositing a non-magnetic seed layer 1501 such as Rh or some other electrically conductive, non-magnetic material. In that case the first sub-layer would be deposited to a such as thickness that the thickness of the first sub-layer 606 plus the thickness of the seed layer 1501 together equal a desired trailing gap thickness. Therefore, the first sub-layer is preferably deposited to a thickness that is less than or equal to (ie. not greater than) a desired trailing gap thickness of the finished write head.

FIGS. 16-18 illustrate a method of constructing a wrap around trailing magnetic shield according to an alternate embodiment of the invention. As shown in FIG. 16, a mask structure 1602 is formed over the magnetic write pole material layer 602.

The mask structure 1602 includes a multi-layer first hard mask structure 1604. This first hard mask structure 1604 includes a first sub-layer constructed of a non-magnetic material that is resistant to ion milling, preferably alumina (Al₂O₃). The first hard mask also includes a second sub-layer formed over the first sub-layer, the second sub-layer being constructed primarily of a material that is resistant to ion milling, but which also contains a material that can be easily detected, such as by SIMS. The second sub-layer 1608 can be constructed of for example alumina with a small amount of a detectable material such as Ti (ie. AlTiO with 1-10 atomic percent Ti.). Such material, when used in the second sub-layer, behave much like a simple alumina hard mask (having excellent ion milling resistance) while also being easily detectable.

As in the previously described example, the mask structure 1602 can include an image transfer layer 612 formed over the hard mask layer and may include a second, or top, hard mask layer 614, and second image transfer layer 616. As before, the first and second image transfer layers 612, 616 can be constructed of a soluble polyimide such as DURAMIDE®, and the top hard mask 614 can be constructed of SiO₂ or some other suitable material. The first image transfer layer 612 can have a thickness of 1000 to 1400 nm or about 1200 nm. The top hard mask can have at thickness of 100 to 130 nm or about 115 nm, and the top, or second, image transfer layer 616 can have a thickness of 60 to 150 or about 90 nm. A photo mask 618 at the top of the mask structure 1602 defines the width of the mask structure 1602.

As described in the above previous embodiment, an ion mill process can be performed to form the write pole 602 and a layer of non-magnetic material (ALD layer) 1202 such as alumina can be deposited by a conformal deposition method, as described previously with reference to FIGS. 12 and 13.

With reference now to FIG. 17, a reactive ion milling 1302 is performed while detecting for the presence of the second sub-layer 1608. When it has been determined that the second sub-layer 1608 has been removed, then milling 1302 can be terminated. The remaining first sub-layer 1606 can then be left intact to provide non-magnetic trailing gap. Then, with reference to FIG. 17, a magnetic material can be deposited to form a trailing wrap around shield 1802 that does not have a notch as the previously described trailing shield did.

While various embodiments have been described, it should be understood that they have been presented by way of example only, and not limitation. Other embodiments failing within the scope of the invention may also become apparent to those skilled in the art. Thus, the breadth and scope of the invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents. 

1. A method for manufacturing a magnetic write head, comprising: providing a substrate; depositing a magnetic write pole material over the substrate; forming a mask structure over the write pole material, the mask structure including a hard mask structure, the hard mask structure including a first sub-layer of material that is resistant to ion milling and a second sub-layer formed over the first sub-layer and comprising a material that is resistant to ion milling and a detectable material; performing an ion milling to remove portions of the magnetic write pole material that are not protected by the mask structure; depositing a non-magnetic side gap material; performing an ion milling and terminating the ion milling when the second sub-layer of has been removed; and depositing a magnetic material to form a trailing shield.
 2. A method as in claim 1 further comprising, while performing the ion milling, performing a detecting operation to detect the presence of the detectable material in the second sub-layer, and terminating the ion milling when the detecting operation determines that the second sub-layer has been removed.
 3. A method as in claim 1 further comprising, while performing the ion milling, performing a Secondary Ion Mass Spectroscopy to detect the presence of the detectable material, and terminating the ion milling when the Secondary Ion Mass Spectroscopy indicates that the second sub-layer has been removed.
 4. A method as in claim 1 wherein the second sub-layer comprises AlTiO.
 5. A method as in claim 1 wherein the second sub-layer comprises AlTiO with 1-10 atomic percent Ti.
 6. A method as in claim 1 wherein the first sub-layer comprises alumina (Al₂O₃) and the second sub-layer comprises AlTiO with 1-10 atomic percent. Ti.
 7. A method as in claim 1, wherein the detectable material comprises an element selected from the group consisting of: Ta, Ti V, Cr, Cu, Zr, Nb, Mo, Ru, Rh, Hr, W, Re, Os, Ir, Pt and Au.
 8. A method as in claim 1 wherein the ion mill resistant material comprises Diamond Like Carbon (DLC) and the detectable material comprises a material selected from the group consisting of: Ta, Ti, V, Cr, Cu, Zr, Nb, Mo, Ru, Rh, Hr, W, Re, Os, It, Pt, and Au.
 9. A method as in claim 1 wherein the ion mill resistant material comprises alumina and the detectable material comprises a material selected from the group consisting of: Ta, Ti, V, Cr, Cu, Zr, Nb, Mo, Ru, Rh, Hr, W, Re, Os, Ir, Pt and Au.
 10. A method as in claim 8 wherein the second sub-layer comprises 1-10 atomic percent of the detectable material.
 11. A method as in claim 9 wherein the second sub-layer comprises 1-10 atomic percent of the detectable material.
 12. A method as in claim 1 wherein the first sub-layer is deposited to a thickness not greater than a desired trailing gap.
 13. A method for manufacturing a magnetic write head, comprising: providing a substrate; depositing a magnetic write pole material over the substrate; forming a mask structure over the magnetic write pole material the mask structure including a hard mask structure that comprises: a first sub-layer comprising a material that is resistant to ion milling; a second sub-layer comprising a material that is resistant to ion milling, but can be removed by reactive ion etching; and a third sub-layer comprising a material that is resistant to ion milling a material that is detectable; depositing a non-magnetic side gap material; performing an ion milling to remove a portion of the non-magnetic side gap material and sufficiently to remove the third sub-layer; performing a reactive ion etch to remove the second sub-layer; and depositing a magnetic, material to form a trailing shield.
 14. A method as in claim 13 further comprising, while performing the ion milling, detecting the presence of the detectable material and terminating the ion milling when all of the third sub-layer has been removed.
 15. A method as in claim 13 further comprising, while performing the ion milling, performing a Secondary Ion Mass Spectrometry (SIMS) to determine when the third sub-layer has been removed and terminating the ion milling when the third sub-layer has been removed.
 16. A method as in claim 13 wherein the third sub-layer comprises AlTiO with 1-10 atomic percent Ti.
 17. A method as in claim 13 wherein the detectable material in the third sub-layer comprises an element selected from the list consisting of: Ta, Ti, V, Cr, Cu, Zr, Nb, Mo, Ru, Rh, Hr, W, Re, Os, Ir, Pt and Au.
 18. A method as in claim 13 wherein the ion mill resistant material comprises Diamond Like Carbon (DLC) and the detectable material comprises a material selected from the group consisting of: Ta, Ti, V, Cr, Cu, Zr, Nb, Mo, Ru, Rh, Hr, W, Re, Os, Ir, Pt and Au.
 19. A method as in claim 13 wherein the ion mill resistant material comprises alumina and the detectable material comprises a material selected from the group consisting of: Ta, Ti, V, Cr, Cu, Zr, Nb, Mo, Ru, Rh, Hr, W, Re, Os, Ir, Pt and Au.
 20. A method as in claim 18 wherein the third sub-layer comprises 1-10 atomic percent of the detectable material.
 21. A method as in claim 19 wherein the third sub-layer comprises 1-10 atomic-percent of the detectable material.
 22. A method as in claim 13 wherein the second sub-layer comprises Si₃N₄, SiO₂ or Ta₂O₅.
 23. A method as in claim 13 wherein the removal of the second sub-layer and the deposition of magnetic material to form the trailing shield results in a trailing shield having a notch not greater than 30 nm deep. 